In a Thin Film Transistor Liquid Crystal Display (TFT-LCD), a gate driving signal is generally provided to a gate of each TFT of a pixel region through a gate driving device so as to control an on/off state of the gate. In order to prevent liquid crystal molecules from being polarized, the LCD should be driven by an alternating driving method. At present, the alternating driving method is mainly realized through providing a source driving voltage in which a positive polarity voltage and a negative polarity voltage appear in an alternating manner to a source of the TFT. The source driving voltage comprises the positive polarity voltage and the negative polarity voltage. The positive polarity voltage is a voltage larger than a reference voltage (which is a common voltage in general), while the negative polarity voltage is a voltage smaller than the reference voltage.
FIG. 1 schematically shows a driving device of a traditional liquid crystal display panel. FIG. 2 is a driving time-sequence diagram of the driving device as shown in FIG. 1. FIG. 3 schematically shows polarities of a pixel voltage in a row inversion driving mode. In the row inversion driving mode, a polarity of a pixel corresponding to adjacent gate lines inverses with a row as a unit.
When a frame m is displayed, a polarity of a pixel voltage corresponding to a gate line in row n is positive, and a polarity of a pixel voltage corresponding to a gate line in row n+1 is negative. As shown in FIGS. 1 and 2, when a gate driving voltage is provided to the gate line in row n, transistors T1, T2, . . . in a same row are all turned on. A positive polarity voltage is written in all pixels corresponding to the gate line in row n, and a writing time is t. After the positive polarity voltage is written, the gate driving voltage is provided to a gate line in row n+1. At this time, transistors T3, T4, . . . in this row are turned on, a negative polarity voltage is written in all pixels corresponding to the gate line in row n+1, and a writing time is also t.
A voltage difference between a positive polarity voltage which is written in the pixels corresponding to the gate line in row n and the gate driving voltage of the gate line in row n is seen as a first voltage difference, while a voltage difference between a negative polarity voltage which is written in the pixels corresponding to the gate line in row n+1 and the gate driving voltage of the gate line in row n+1 is seen as a second voltage difference. When the gate is turned on, the first voltage difference is unequal to the second voltage difference. Therefore, the pixels corresponding to the gate line in row n would have a different charging effect from the pixels corresponding to the gate line in row n+1 when they have a same writing time. As a result, an image displayed in the liquid crystal display panel would have a non-uniform brightness, and a display effect thereof would be adversely affected.